If you’re unfamiliar with TypeScript, I’d highly recommend checking it out. It’s my new preferred way to write JavaScript based applications.

If you write an application in TypeScript and need to interact with an external set of either JavaScript or C++/CX dependencies then you will quickly find that you are going to be mucking with some TypeScript Definition files and the more you take a dependency on the WinRT runtime the more type definitions you probably need to manually create.

It’s true that the TypeScript team has created a set of TypeScript Definition files for WinRT and WinJS, but I couldn’t get any comment as to how they were generated. And the more I looked into what was provided, the more I realized that there were inconsistencies and inaccuracies that were not good. Which led me to believe that they weren’t working on a super-secret tool to automatically generate these for us.

ToTypeScriptD is a quick little attempt at automatically taking the type system provided to us by a C++/CX winmd or .Net assembly file and projecting that into a set of TypeScript Definition files. This tool can basically take anything that is Ecma 355 Common Language Infrastructure (CLI) and spit out a .d.ts file for you automatically.

Why would I need this?

In the project readme I describe two use-cases that I know of (so far).

If you build a 'Modern' (come on, we still call it Metro) Windows 8 app with WinJS and want to leverage TypeScript, wouldn't it be nice to get a set of TypeScript Definition files that reflect the native API's you're calling in the platform without manually creating the definition files?

Say your building an MVC/WebAPI server application. It would be useful if your C.I./Build system could generate a set of TypeScript interfaces that were based on the server objects used to render your JSON API. This can be useful for client side JavaScript/TypeScript libraries that need to consume these objects and also provide a simple way to document the format of the input and output API response objects.

How do I get the project and start using it?

Before you install the tool and dive in head first, I would like warn you that I have only been working on this for about 2 weeks (in my off-hours) and there is going to be lots of room for improvement. But it’s currently generating a solid set of .d.ts files for .winmd files.